You go to Brixton market and ask for calves’ feet, and the butcher presents you with what looks like a bundle of old rope, bristling with coarse hair and knotted with cartilage. They have the weight and heft of logs; the butcher ties them in a bundle with twine, and you drag them home.

You don’t have a big enough pot to cook them, so back at your flat you get out every pan you own and put the feet on to boil. The water turns the colour and opacity of mud, and the house fills with the gluey smell of hot fat. The knobbliest bits of the feet – once knees and ankles – bob up from under the water, and when you strain them, they hit the sink with a hollow thud.

Then comes the alchemy. You put the stock back on the boil and whisk up some egg whites into stiff, dry peaks. You carefully spread them over the top of the pan, and they darken into a dirty grey, the colour of several day-old city snow. The whites, for some magical reason, absorb every grain of scum in the stock, so that when you strain it again, through a colander lined with a tea-towel, the jelly gushes out a clear, light amber. You ladle it into a Tupperware, put it in the fridge to set, and the next day you put it in a bag and catch the bus to David’s.

I am meeting my daughter Laura for lunch. Her matter, once so desperately knitted to my own, is now so independent that I only see her once a month; the dot of jelly I once carried within me is now a fully qualified doctor, riding her bike to hospital as the sun comes up every morning. She arrives, as always, in mock high dudgeon about something; this time that her appalling housemate Sophie has just started ‘eating clean’.

(Imitating Laura imitating Sophie’s nasal posh-girl whine)

‘“I just think it’s so important to be aware of where stuff is from before you put it in your body, so that you’re not clogging your system with stuff it doesn’t need.” It’s all bollocks, obviously. I know it’s only about losing weight, but she has spaff on about her lifestyle and her intentions.”

‘I suppose it’s better that than crash dieting,’ I say, knowing that she wants me to play devil’s advocate so that she can argue.

She rolls her eyes. “It’s so Catholic. Like food is some kind of original sin that we’ve got to absolve ourselves from. There’s zero science to it.’

‘People create their own religions,’ I say. ‘They need to.’

She grimaces, shovels in another heaped forkful of risotto.

None of us can ever be sure of the moment when David adopted us. We had all applied to our course hoping to be taught be him; even then, his reputation preceded him, the sexy young upstart massacring the course’s sacred cows, raging against the faculty; so of course, when we did end up in his class in our first term, we were comically mousy, squeaking our way through his supervisions.

He was impatient, but amused; and at the end of term, he invited us to Christmas drinks, and then on some very complicated walk he was doing for research along the Docklands in the new year, and then to dinner about once a month. It wasn’t embarrassing and down with the kids; David was born without the need to ingratiate himself with anyone. I have never known anyone with rigour quite like David’s: he could skewer the phony, the glib, the trite, with one swish, impaling them on his wit like a kebab. And he would make you do the same: I remember leaving his supervisions feeling that my hair must have turned white from thinking so hard.

The dinners carried on after we’d graduated. David would tip some tinned mushrooms into a curry sauce – he had that academic’s disdain for good food that we all found so punk and glamorous back then – and I would bring pudding. David never complimented my food – not to be rude, it just didn’t register with him – but I liked to wordlessly bring tribute with me every time, like a magi.

We all realised that David was ill at different times, and I found out last; none of us shared this kind of thing with each other because, being young, we were hesitant to seem worried in front of each other. It took Nick letting it slip to me on the bus over to one of David’s dinners, after I’d wondered aloud why we hadn’t seen him over the summer.

‘He’s been ill,’ said Nick finally, queasily. It was the early days of our going out, and Nick was still very young, and he always handled me at arm’s length if he had to tell me something that might upset me.

‘What sort of ill?’ I asked, ‘Is it serious?’

He frowned and made a lot of muffled noises, about how they don’t know and they're running tests. I looked down at the trifle I was holding in my lap and dared myself to ask more, but didn’t.

The party was in full swing when we got there. I scanned David’s face when I was certain that he wouldn’t catch me. He looked tired, perhaps, thinner, but he wasn’t any less animated – actually, his conversation was particularly brilliant that night, burning with a hotter, brighter flame. When dinner was over we took our drinks into the study to look at his bookshelves, and him and Nick got into one of their usual affectionate set-tos.

‘It’s so lame,’ David was thundering about Walt Whitman, ‘The spider on the edge of the universe. Tossing off his filament into the abyss. Fucking wanker.’ Nick was furious but doubled over with laughter; they were arguing in that giggling, slightly flirtatious way, daring each other on to bolder flights of rudeness.

I wandered over to David’s desk to look at the books he had open on it, and to my surprise they were all old cookery books. David looked over and caught my eye.

‘I’ve been meaning to ask you about this project of mine, Gillian,’ he said, ‘Given that you’re chef of the group.’

He’d dog-eared all of them on pages about jelly. Not sweet jelly, but savoury jellies, those mud-coloured Edwardian monstrosities made from boiled up animal bones.

I looked up, and saw he was still looking at me.

‘Would you make me one?’ he asked. ‘And bring it over? Just us. On one of my days.’

I turned up at his a few weeks later at lunchtime with my offering. He answered the door in his pyjamas, and in the time since I had seen him last the stairs back up to his flat had become difficult for him to manage. He laid the table while I spooned us quivering platefuls. The jelly was cool and slithery, like silk underwear if silk underwear was disgusting, and once you’d chased it around your plate and got some in your mouth it tasted – why was I surprised? – of hoof.

And David’s brightness came back while he was eating; he chatted away, occasionally closing his eyes to slowly swallow and savour this disgusting thing. And while I was stacking the plates he took my hand and kissed it, and said, ‘Just the thing. Thank you.’

It wasn’t just the ticket, of course. He didn’t ask me to make it again, and a year later he was dead.

Mine was one afternoon spent with David over his rich life and short illness; it is a lasting memory, but by no means a definitive one. On the train on the way to his funeral the silence panicked me, and clumsily I sought to fill it, suggesting that we all volunteer a memory of David – when Nick, red-eyed and already drunk, cut across me.

‘David would have found this embarrassing.’

It was cruel, but he was right. David would have been mortified that after all the critical thought he had bred in us, we had fallen for the cheap séance of nostalgia, conjuring up a pallid ghost of him from a handful of anecdotes.

Our group splintered gratefully once we reached the reception, longing to get away from each other and talk to anyone else. I drank, and grew promiscuous with my confidences; I ended up trapping some stodgy-faced young man who turned out to be one of David’s much-disdained suburban cousins by the buffet table and telling him about the jelly, and to my surprise he grew very excited. Perhaps a latent manifestation of his discarded Jewishness, the cousin said hopefully – didn’t I know that calves’ foot jelly was a staple of Ashkenazi cuisine?

I was nonplussed; I couldn’t think of anyone less susceptible to ‘getting’ religion than David. If we were going to do right by him, Nick would tell me that night, his face pulpy with tears and drink, we were going to keep on thinking like he’d taught us: toughly, unsentimentally, empirically. We were going to look his illness in the face and, by knowing it and naming it, conquer it; not distract ourselves with superstition, with sentimentality, with crap.

It is easy to look back on David and me, chasing animal gelatine around our plates at his kitchen table, as participating in a peculiar kind of worship. To David, the rites of extracting the impurities embedded in another animal’s bones - the laborious paring of bone from flesh and then marrow from bone - and putting what was left into his faltering body might enact a kind of magic: he was Egypt beset by the plagues, and only weird old taboos of purity could save him. David and I, stabbing at our slithery puddles of marrow, were stabbing in the dark, in the shadow cast by a new, merciless god.

Humans don’t outgrow themselves, I want to say to Laura. Eating clean is a fashion, but it’s nothing new. We can develop our critical faculties as much as we like, but we can’t surpass these bodies, these bodies that are and aren’t us, and our powerful and misguided notions of their purity and impurity. David couldn’t: neither faith nor knowledge, magic nor science, could save him; neither side gets to claim him as a spoil of war.

He had a body, and he had a mind, and in trying to make sense of the two, he was human. He was Whitman’s spider – not noiseless or patient, but launching filament, filament, filament of himself out into the universe to see what might catch and connect.

But rather than telling her this, I fill up her wine glass, and push the food that’s left on my plate on to hers, and start to tell her a story, about a light that was in my life, that lit up my universe, and how bright and hot it glowed. Our hour is short, and nearly spent; and yet there is time for this, the spinning and launching of another story out into the space between us.